Printed tissue will be repopulated with healthy tissue, will dissolve within two to three years

Amidst the controversy over 3D printing and gun control, it's important to remember that the potential of the former device goes far beyond making weapons.  

I. Baby Blues

That's the story of a baby Kaiba, who suffered from a rare disease called tracheobronchomalacia.  Often misdiagnosed as asthma, the disease in some cases isn't as severe, outgrown by age 2 or 3.  But in Kaiba's case the disease was more severe; while 1 in 2,200 babies (appr.) have the lesser form, only around 1 in 20,000 have the more serious version he had.

Kaiba's parents April and Bryan first detected the condition when he was six-weeks old.  They were enjoying a meal at a restaurant when their watchful eyes noticed their child was struggling to breathe and turning blue.  They rushed him to a hospital.

For the next several weeks baby Kaiba continued to stop breathing and turn blue requiring resuscitation.  With his bronchus -- part of the lung's air-tubing system -- collapsing regularly, his chances looked bleak.  Recalls April, "Quite a few doctors said he had a good chance of not leaving the hospital alive.  At that point, we were desperate. Anything that would work, we would take it and run with it."

The Ohio family took their baby to the University of Michigan's Mott Children’s Hospital to explore an advanced treatment option.

Mott childrens
Mott's Children Hospital, Ann Arbor, Mich.

Glenn Green, M.D., an associate professor of pediatric otolaryngology at the school, who helped treat him.  He comments, "Severe tracheobronchomalacia has been a condition that has bothered me for years.  I've seen children die from it.  Even with the best treatments available, he continued to have these episodes. He was imminently going to die. The physician treating him in Ohio knew there was no other option, other than our device in development here."

II. Printing a New Bronchus

The "device" in question was a 3D-printed organ formed from a biocompatible polymer known as polycaprolactone (PCL).  PCL is growing in popularity in tissue engineering studies as it is generally gentle on the body and dissolves within two to three years -- providing structural support while the body recolonizes a damaged tissue.

Polycaprolactone is produced from caprolactone, a cyclic compound found in heated milk fat.
[Image Source: Wikimedia Commons]

Scott Hollister, Ph.D., professor of biomedical engineering and mechanical engineering and associate professor of surgery at U-M comments, "The material we used is a nice choice for this. It takes about two to three years for the trachea to remodel and grow into a healthy state, and that's about how long this material will take to dissolve into the body."

Normally implanting a PCL 3D-printed organ in the U.S. would be illegal -- even if it had the potential to save a life -- due to the convoluted mess of bureaucracy and red tape that is the U.S. Food and Drug Administration.  But Kaiba's parents took their child to the right place; U-of-M had close relationships with federal regulators, which allowed them to obtain an emergency exemption to test a bronchus implant on Kaiba.

Bronchus printed
The printed 3D bronchus implant [Image Source: U-of-M]

The implant was a resounding success.  Fashioned from CT scans of the baby's own bronchus and sculpted by lasers in the 3D printer, the new tissue was sewn into place without complications.  Recalls Dr. Green, "It was amazing. As soon as the splint was put in, the lungs started going up and down for the first time and we knew he was going to be OK."

Within 21 days the youngster was off ventilation and breathing in sweet air thanks to his groundbreaking new implant.  He's had no breathing problems since, and is expected to grow a healthy bronchus, making a transition into healthy adolescence.

III. PCL Promising for Other Tissue Replacements

The case was so astounding that the doctors published [PDF] a peer-reviewed article on it in the top medical journal New England Journal of Medicine.  Dr. Hollister cheers, "Kaiba's case is definitely the highlight of my career so far. To actually build something that a surgeon can use to save a person's life? It's a tremendous feeling."

Drs. Green and Hollister are racing to apply 3D printed PCL structures to other forms of soft-tissue recovery including ear and nose structures, which are in preclinical model trials.  They also are examining using the biopolymer in bone structures (spine, craniofacial and long bone).

PCL is being explored to replace other soft tissues like nose cartilage.
[Image Source: MakeCoconut]

And interesting side note -- in a way this is a case of "patient heal thyself".  The monomer precursor to PCL (polycaprolactone) is founded in heated mammalian milk fat and is polymerized via a ring opening process.  Hence a product of a biochemical found in humans and other mammals is now being applied via advanced technology to saving human life.

Sources: U of M [1], [2], New England Journal of Medicine

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